People like that need to be in control. The more they see a person as vulnerable, the more they will try to control situations and they are extremely self involved. Personally I think that people like this tend to be predatory and latch on to those that they see as "weak" or easy "targets" because they can see the target has a vulnerability or a gentle nature. I sadly was once married to someone who was a narcissist although they were not violent at all thankfully. There are many different forms of control though. My State just passed new laws regarding what is called Coercive Control. It is now criminalised.

Friend, this person who has treatened you on multiple occasions needs to be reported and please keep everything that has happened in writing. Having an illness or condition does not give someone the right to abuse you or control your movements in your own home.